COORDINATED FAST/GEOTAIL OBSERVATIONS OF MAGNETOSPHERE-IONOSPHERE COUPLING

K. Sigsbee¹, C. Cattell¹, R. Lysak¹, F. Mozer², C. Carlson², R. Ergun², J. McFadden², K. Tsuruda³, T. Yamamoto³, T. Okada⁴, S. Kokubun⁵, D. Fairfield⁶, R. Strangeway⁷, G. Parks⁸, M. Brittnacher<sup>8

1</sup>School of Physics and Astronomy, University of Minnesota, Minneapolis, MN USA
²University of California, Berkeley
³ISAS
⁴Toyama Prefectural University
⁵STELAB, Nagoya University
⁶NASA/GSFC
⁷UCLA
⁸University of Washington, Seattle, WA

Abstract. During January and February 1997, a number of conjunctions between the FAST and Geotail satellites occurred when FAST was at apogee above the nightside auroral zone in the northern hemisphere and Geotail was close to midnight near the equatorial plane. These events provided an opportunity to examine physical processes connecting the magnetotail at 20 to 40 RE to the auroral zone during substorms and quiet times. We present results from conjunctions on January 18, 1997 [Sigsbee et al., 1998] and February 3, 1997. Images from Polar were available during both events. Comparison of waves observed by Geotail and FAST on January 18 provided evidence for magnetosphere-ionosphere coupling via Alfvén waves, as well as the near simultaneous occurrence of waves in other frequency bands. Similar results were obtained during the February 3, 1997 conjunction. These observations are significant to the verification and further development of magnetosphere-ionosphere coupling models.